import java.util.LinkedList;
import java.util.Queue;

public class MyStackUseQueue {
    Queue<Integer>qu1;
    Queue<Integer>qu2;
    public MyStackUseQueue() {
        qu1=new LinkedList<>();
        qu1=new LinkedList<>();
    }

    public void push(int x) {
        if(!qu1.isEmpty()){
            qu1.offer(x);
        }else if(!qu2.isEmpty()){
            qu2.offer(x);
        }else {
            qu1.offer(x);
        }

    }

    public int pop() {
        if(empty()){
            return -1;
        }
        if(!qu1.isEmpty()){
            int size= qu1.size();
            for (int i = 0; i <size-1 ; i++) {
                int val=qu1.poll();
                qu2.offer(val);
            }
            return qu1.poll();
        }else {
            int size= qu2.size();
            for (int i = 0; i <size-1 ; i++) {
                int val=qu2.poll();
                qu1.offer(val);
            }
            return qu2.poll();
        }

    }

    public int top() {
        if(empty()){
            return -1;
        }
        if(!qu1.isEmpty()){
            int tmp=0;
            int size= qu1.size();
            for (int i = 0; i <size ; i++) {
                tmp=qu1.poll();
                qu2.offer(tmp);
            }
            return tmp;
        }else{
            int tmp=0;
            int size= qu2.size();
            for (int i = 0; i <size ; i++) {
                tmp=qu2.poll();
                qu1.offer(tmp);
            }
            return tmp;
        }

    }

    public boolean empty() {
        return qu1.isEmpty()&&qu2.isEmpty();

    }
}


